Power supply method and electronic card using the same

ABSTRACT

Provided is a power supply method for efficient operation of electronic cards and an electronic card using the same, and the power supply method may include the steps of: charging a charging unit through the DC power supplied from a rectification unit; enabling, when a constant voltage enable signal is applied, a system constant voltage unit if a predefined condition is satisfied; and supplying power to a system unit when the system constant voltage unit is enabled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to a KoreanPatent Application No. 10-2017-0111421 filed Aug. 31, 2017, in theKorean Intellectual Property Office, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The present disclosure is related to a power supply method for efficientoperation of electronic cards and an electronic card using the same, andmore particularly, relates to a power supply method using an energyharvesting circuit and an electronic card using the same.

Getting out of the method of a conventional magnetic card which recordscard information on a magnetic stripe, a smart card may store theinformation in an integrated circuit (IC) chip and includes varioustypes of card, such as a card giving and receiving information in acontact or contactless method, a hybrid card and a combination card.Meanwhile, the smart card may have a secure element with improvedsecurity since various secure information for making a payment is storedtherein.

As the smart cards are also used for transaction certification or userauthentication, as well as payment, they are developed as electroniccards of various forms by adding a one-time password (OTP) function, abioinformation recognition function or the like.

As various functions are added to the electronic cards unlike existingsmart cards, each component of the electronic cards consumes power, andthe electronic cards employ a method of using its own battery. However,since the size, run time, charging method or the like of the batterydoes not meet conditions for commercializing the electronic cards,powerless electronic cards are developed recently. As a prior technique,a powerless information processing device of Korea Patent RegistrationNo. 10-0537903 shows an example of a powerless IC card.

SUMMARY

Therefore, the present invention has been made in view of the problemsof the conventional electronic cards provided with a battery, and it isan object of the present disclosure to provide a power supply method foraccomplishing efficient supply of power and operation of powerlesselectronic cards and an electronic card using the same.

A first aspect of the present disclosure relates to a power supplymethod implemented in an electronic card, and the power supply methodmay include the steps of charging a charging unit through DC powersupplied from a rectification unit, enabling, when a constant voltageenable signal is applied, a system constant voltage unit if a predefinedcondition is satisfied, and supplying power to a system unit when thesystem constant voltage unit is enabled, wherein the system constantvoltage unit receives the DC power together with the charging unit andmay be in a disabled state until the constant voltage enable signal isreceived.

A second aspect of the present disclosure relates to an electronic cardusing the power supply method, and the electronic card may include, arectification unit for generating DC power by converting current inducedfrom an antenna, a charging unit charged with the DC power supplied fromthe rectification unit, a system constant voltage unit for receiving theDC power together with the charging unit, being in a disabled stateuntil a constant voltage enable signal is received, being enabled when apredefined condition is satisfied, and supplying power to a system unit;and the system unit for receiving power and operating when the systemconstant voltage unit is enabled.

At this point, the predefined condition may include a first conditionthat the charging unit has a charged capacity higher than a predefinedreference value and a second condition of receiving the constant voltageenable signal from the rectification unit.

In addition, the electronic card may further include a voltage levelrecognition unit for monitoring a power supply state to determinewhether the predefined condition is satisfied, and the voltage levelrecognition unit may determine whether the predefined condition issatisfied and transmit an enablement signal to the system constantvoltage unit if the predefined condition is satisfied.

The system unit may include a module for implementing at least oneapplication function provided by the electronic card and operate usingthe power received from the system constant voltage unit.

As another embodiment, the predefined condition may further include athird condition of supplying power through a contact-type interface ofthe electronic card, and if power is supplied through the contact-typeinterface, the voltage level recognition unit may determine that thepredefined condition is satisfied and enable the system constant voltageunit.

In addition, the electronic card may further include a system interfaceunit for grasping an applied power state and a power use state of thesystem unit and transferring the states to the voltage level recognitionunit, and the system interface unit may include: a system NFCrecognition unit for sensing a wireless communication signal receivedfrom the rectification unit; and a system power control unit fortransmitting a power supply maintaining signal to the voltage levelrecognition unit when power of the system unit needs to be maintained.

Here, the system power control unit may receive a potential levelreduction signal from the system NFC recognition unit and transmit thepower supply maintaining signal to the voltage level recognition unit ifit is determined that power of the system unit needs to be maintained.

According to an embodiment, when the power supply maintaining signal isreceived, the voltage level recognition unit may enable the systemconstant voltage unit for a predetermined time period regardless ofwhether the predefined condition is satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of an electroniccard according to a first embodiment of the present disclosure.

FIG. 2 is a block diagram showing the configuration of an electroniccard according to a second embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a power supply method of anelectronic card according to a second embodiment of the presentdisclosure.

FIG. 4 is a block diagram showing the configuration of an electroniccard according to a third embodiment of the present disclosure.

FIG. 5 is a flowchart illustrating a power supply method of anelectronic card according to a third embodiment of the presentdisclosure.

FIGS. 6A and 6B are exemplary views showing the configuration of anelectronic card according to an embodiment of the present disclosure.

In a plurality of drawings, like reference numerals indicate likecomponents.

DETAILED DESCRIPTION

In the present disclosure, as a specific structural or functionaldescription given to embodiments in accordance with concepts of thepresent disclosure will be illustrated for the purpose of describingonly embodiments according to the concepts of the present disclosure,the embodiments according to the concepts of the present disclosure maybe embodied in various forms, but should not be limited the embodimentsdescribed herein.

Since the embodiments according to the concepts of the presentdisclosure may be embodied in many different forms, these embodimentswill be described in detail with reference to accompanying drawings.However, these embodiments according to the concepts of the presentdisclosure should not be construed as being limited to the embodimentsset forth herein. Accordingly, those of ordinary skill in the art willrecognize that modification, equivalent, and/or alternative on thevarious embodiments described herein can be variously made withoutdeparting from the scope and spirit of the present disclosure.

The terms, such as “first”, “second”, and the like used herein may referto various elements of various embodiments of the present disclosure,but do not limit the elements. Such terms may be used to distinguish oneelement from another element. For example, without departing the scopein accordance with the concepts of the present disclosure, a firstelement may be referred to as a second element, and similarly, a secondelement may be referred to as a first element.

It will be understood that when an element is referred to as being“(operatively or communicatively) coupled with/to” or “connected to”another element, it can be directly coupled with/to or connected to theother element or an intervening element may be present. In contrast,when an element is referred to as being “directly coupled with/to” or“directly connected to” another element, it should be understood thatthere are no intervening element. Similarly, words such as “between”,“directly between”, “adjacent to”, “directly adjacent to”, and the likeshould be interpreted in a like fashion.

Terms used in this specification are used to describe embodiments of thepresent disclosure and are not intended to limit the scope of thepresent disclosure. The terms of a singular form may include pluralforms unless otherwise specified. The term “include,” “comprise,”“including,” or “comprising” used herein indicates disclosed functions,operations, or existence of elements but does not exclude otherfunctions, operations or elements. It should be further understood thatthe term “include”, “comprise”, “have”, “including”, “comprising”, or“having” used herein specifies the presence of stated features,integers, operations, elements, components, or combinations thereof butdoes not preclude the presence or addition of one or more otherfeatures, integers, operations, elements, components, or combinationsthereof.

Unless otherwise defined herein, all the terms used herein, whichinclude technical or scientific terms, may have the same meaning that isgenerally understood by a person skilled in the art. It will be furtherunderstood that terms, which are defined in a dictionary and commonlyused, should also be interpreted as is customary in the relevant relatedart and not in an idealized or overly formal sense unless expressly sodefined herein in various embodiments of the present disclosure.

FIG. 1 is a block diagram illustrating the configuration of anelectronic card 100 according to an embodiment of the presentdisclosure. An electronic card 100 may include an antenna 50, arectification unit 10 for generating DC power by converting RF or NFCsignals received by the antenna, a charging unit 20 for storing the DCpower, a system unit 40 for operating various electronic circuits addedto a smart card, and a system constant voltage unit 30 for supplyingstable voltage to the system unit. Since the electronic card 100according to an embodiment of the present disclosure is a powerlesselectronic card and supplies power to the system unit 40 using therectification unit 10, the charging unit 20 and the system constantvoltage unit 30, the components 10 and 20 or 10 to 30 may be named as anenergy harvesting circuit or an energy harvester.

The antenna 50 performs a function of receiving RF signals wirelesslytransmitted from a contactless-type card reader installed outside. Forexample, when the contactless-type card reader loads a data on an ACsignal or a carrier wave having a predetermined frequency, the currentflowing through an RF antenna provided in the card reader is convertedinto a wireless signal, and induced current is generated in the antenna50 provided in the smart card according to an electromagnetic inductionphenomenon.

Although a single antenna 50 may be provided in the electronic card 100in an embodiment, in another embodiment, the electronic card 100 may beimplemented to include two or more antennas such as a power antenna, acommunication antenna and the like. For example, the electronic card 100is separately provided with a system driving antenna for supplying powerto the system and an antenna dedicated to a smart card chip and has astructure of physically separating these two antennas from each other,and it is configured not to use the system driving antenna in wirelesscommunication for data transmission, but to use only for receivingpower. According to this, there is an effect of increasing the capacityof power that the smart card receives from the card reader and improvingstability of RF communication between the card reader and the smartcard.

The rectification unit 10 is a component for generating DC power byconverting the current induced from the antenna 50 and may beimplemented, for example, in the form of a rectification circuit using adiode. Since the current induced from the antenna 50 is AC currentwhereas the system unit 40 which needs power operates using DC power,the rectification unit 10 converts the RF signals received from theantenna 50 into DC power.

The charging unit 20 is a means for storing the DC power supplied fromthe rectification unit 10 and may be implemented, for example, as asecondary cell or a super capacitor. The super capacitor is particularlyfocused on improving performance of electric capacity among theperformances of a capacitor (condenser) and may be used for the purposeof a battery, and a capacitor used in an electronic circuit has afunction electrically the same as that of a rechargeable battery. In anembodiment, the charging unit 20 may be charged with the DC powerapplied from the rectification unit 10 and may be implemented to chargeto the capacity of the charging unit 20 in a short time, for example,about one second, and thus spontaneous power needed for system operationmay be accumulated in the charging unit 20 only by contacting theelectronic card 100 to the reader for a short time period.

The system constant voltage unit 30 is a component for supplying powerto the system unit 40 by a predefined signal and may be implemented, forexample, using a transistor, a field effect transistor (FET), a switch,a regulator or the like. In an embodiment, the system constant voltageunit 30 may be implemented to be enabled only when power is suppliedfrom NFC and supply power to the system unit 40.

In a general circuit of the prior art, it is general that power issupplied to the charging unit and the system constant voltage unit atthe same time, and the power supplied to the system constant voltageunit is also transferred to the system unit. When the charging unit andthe system unit are supplied with power at the same time like this, thecharging time is extended as much as the time of supplying power to thesystem. In addition, since the system operates at a potential lower thanan operation potential in some cases, there is a problem of occurring amalfunction and consuming current more than general consumption ofcurrent as the system becomes instable.

The present disclosure is a technique devised to solve the problems, andalthough DC power is supplied to the charging unit 20 and the systemconstant voltage unit 30 at the same time, the system constant voltageunit 30 may be configured to operate in a disabled state until thecharged capacity of the charging unit 20 reaches a reference value.While the charging unit 20 is charged more than the reference value, thesystem constant voltage unit 30 may be enabled by a constant voltageenable signal generated when NFC power is applied. Here, the constantvoltage enable signal includes a DC power signal according to apredetermined reference. If the system constant voltage unit 30 isenabled, it also supplies power to the system unit 40.

According to the power supply method as described above, since thecharging unit 20 does not supply power to the system unit if there is noconstant voltage enable signal, natural discharge does not occur, andpower remains. Then, since the remaining power and the power suppliedfrom the NFC are used when a transaction is made, charging time of thecharging unit 20 is relatively shortened.

The system unit 40 operates using the DC power supplied from the systemconstant voltage unit 30 and may include components for operatingvarious application modules added to the smart card. For example, whenthe smart card is provided with a display for displaying a balance or atransaction status, the system unit 40 may include a display module andan MCU module for driving the display module. Since the system unit 40of the present disclosure receives power and operates only when thesystem constant voltage unit 30 is enabled, it may perform stableoperation without generating a malfunction at a low potential.

Like this, the present disclosure may adjust supply of power to thesystem unit 40 by selectively enabling or disabling the system constantvoltage unit 30. In addition, there is an effect of accomplishingreduction of charging time and a stable charged capacity by intensivelycharging the charging unit 20 when the system constant voltage unit isdisabled.

Although not shown in the figure, the electronic card 100 may furtherinclude components such as a Micro Processor Unit (MPU) having its ownoperation function, Read Only Memory (ROM) for storing a Chip OperationSystem (COS), Electrically Erasable Programmable Read Only Memory(EEPROM) for storing application programs and data thereof, RandomAccess Memory (RAM) for temporarily storing data including a variety ofvariables, an I/O interface for exchanging data with the outside of thesmart card chip and the like.

In addition, although it has been described focusing on the operationaccording to contactless communication using an antenna in the firstembodiment, it is not limited thereto, and this embodiment may beapplied even when DC power is received through a contact-type interface.

FIG. 2 is a block diagram showing the configuration of an electroniccard according to a second embodiment of the present disclosure. In amanner the same as described in the first embodiment, an electronic card200 may include an antenna 50, a rectification unit 10 for generating DCpower by converting RF or NFC signals received by the antenna, acharging unit 20 for storing the DC power, a system unit 40 foroperating various application modules added to a smart card, and asystem constant voltage unit 30 for supplying stable voltage to thesystem unit. In addition, the electronic card 200 according to a secondembodiment may further include a voltage level recognition unit 60 forenabling the system constant voltage unit 30.

In a manner the same as described in the first embodiment, when theelectronic card 200 performs contact or contactless communication with areader, it converts the current received through the antenna 50 into DCpower through the rectification unit 10 and supplies the DC power to thecharging unit 20 and the system constant voltage unit 30 at the sametime. At this point, the system constant voltage unit 30 may beimplemented to operate in a disabled state until the charged capacity ofthe charging unit 20 reaches a reference value. While the charging unit20 is charged more than the reference value, the system constant voltageunit 30 may be enabled by a constant voltage enable signal generatedwhen NFC power is applied. When the system constant voltage unit 30 isenabled, it also supplies power to the system unit 40.

According to the power supply method as described above, since the powerremaining in the charging unit 20 and the power supplied from NFC areused, charging time is shortened. Since the components 10 to 50described above operate in a manner the same as described in the firstembodiment, detailed descriptions thereof will be omitted.

The voltage level recognition unit 60 is a module for monitoring a powerapply state and determining whether the system constant voltage unit 30is enabled and may be configured as a semiconductor chip, a circuit orthe like. The voltage level recognition unit 60 may sense a voltagelevel of the charging unit 20 and sense the constant voltage enablesignal generated when NFC power is applied. In an embodiment, thevoltage level recognition unit 60 may monitor whether the voltage of thecharging unit is equal to or higher than a reference value (e.g., 2.3V).

A power supply method using the voltage level recognition unit 60 isdescribed in further detail with reference to FIG. 3. Referring to FIG.3, if DC power is supplied through the rectification unit 10 when poweris applied through a reader, the charging unit 20 may be charged (stepS310). For example, the DC power can be used only to charge the chargingunit. However, when the charging unit 20 is charged thereafter, sincethere is remaining power in the charging unit 20, charging time isminimized, and thus the system constant voltage unit 30 may be enabledimmediately when NFC power is applied through the reader.

The voltage level recognition unit 60 may monitor whether the constantvoltage enable signal is applied (a first condition) and the chargedcapacity of the charging unit 20 (a second condition) (steps S320 andS340). Although it is shown in FIG. 3 that whether the charged capacityis higher than a reference value is determined after determining firstwhether the constant voltage enable signal is applied, it is not limitedthereto, and it may be implemented to change the order of steps S320 andS340 or to perform the steps simultaneously. In the embodiment of FIG.3, the voltage level recognition unit 60 may determine whether theconstant voltage enable signal is generated through wirelesscommunication such as NFC, and determine whether the charged capacity ofthe charging unit 20 is higher than a predetermined reference value whenthe constant voltage enable signal is applied. The voltage levelrecognition unit 60 may transfer an enablement command to the systemconstant voltage unit 30 when both the first condition related to theconstant voltage enable signal and the second condition related to thecharged capacity are satisfied. Contrarily, when the constant voltageenable signal is not applied or the charged capacity is lower than thereference value, the voltage level recognition unit 60 may maintain thedisabled state of the system constant voltage unit 30 (step S330).

If the system constant voltage unit 30 is enabled, the applied power issupplied to the system unit 40 through the system constant voltage unit30 (steps S350 and S360). The system unit 40 may be supplied with thepower and operate various functions of the electronic card 200.

Through the power supply method as described above, the charging time ofthe charging unit 20 can be reduced to the maximum, and stable operationof the system unit 40 can be supported. In addition, it is implementedto prevent natural discharge of the power of the charging unit 20 and tosupply power to the system unit 40 only when NFC power is applied.

In relation to the second embodiment, FIGS. 6A and 6B are exemplaryviews showing the configuration of an electronic card according to anembodiment of the present disclosure. In the embodiment, an electroniccard 600 may be implemented to include an antenna 50, a rectificationunit 10, a charging unit 20, a voltage level recognition unit 60, asystem constant voltage unit 30 and a system unit 40 and may furtherinclude a security element (SE) 620 and a COB pad 610 of the electroniccard 600. The security element 620 is a secure element and performsvarious functions for processing, storing and encrypting informationwhich needs security in operating the electronic card 600. The COB pad610 is connected to a contact terminal of the security element 620 andmay supply communication data or power to the security element 620through a reader.

Meanwhile, to supply power to the system unit 40 which performs variousapplication functions according to an embodiment of the presentdisclosure, the charging unit 20 is charged if DC power is appliedthrough the rectification unit 10, and enablement or disablement of thesystem constant voltage unit 30 is determined according to thedetermination of the voltage level recognition unit 60. As describedabove, the voltage level recognition unit 60 determines whether aconstant voltage enable signal is generated through wirelesscommunication such as NFC and determines whether the charged capacity ofthe charging unit 20 is higher than a preset reference value.

If both the condition of applying the constant voltage enable signal andthe condition of the charged capacity higher than the reference valueare satisfied, the voltage level recognition unit 60 may transfer anenablement command to the system constant voltage unit 30. Contrarily,if the constant voltage enable signal is not applied or the chargedcapacity is lower than the reference value, the voltage levelrecognition unit 60 may maintain the disabled state of the systemconstant voltage unit 30. If the system constant voltage unit 30 isenabled, the applied power is supplied to the system unit 40 through thesystem constant voltage unit 30.

As shown in FIGS. 6A and 6B, the voltage level recognition unit 60 maybe arranged between the rectification unit 10 and the charging unit 20to sense the charged capacity of the charging unit 20 and a signalapplied through the rectification unit 10 and connected to the systemconstant voltage unit 30 to transfer the enablement signal. In anembodiment, although the voltage level recognition unit 60 and thesystem constant voltage unit 30 are shown as separate components, thecomponents 60 and 30 may also be implemented in an integrated form.

In addition, although it has been described focusing on the operationaccording to contactless communication using an antenna in a manner thesame as described in the first embodiment, it is not limited thereto,and this embodiment may be applied even when DC power is receivedthrough a contact-type interface.

FIG. 4 is a block diagram showing the configuration of an electroniccard 400 according to a third embodiment of the present disclosure, andFIG. 5 is a flowchart illustrating a power supply method of theelectronic card according to a third embodiment of the presentdisclosure. The third embodiment relates to a configuration additionallyincluding a system interface unit 70 in the configuration of theelectronic card 200 described in FIG. 2.

The system interface unit 70 is a component for supplying power to thesystem unit 40 even when the system constant voltage unit 30 does notsatisfy the enablement condition and may transfer a signal forrequesting supply of power in a predetermined case. In an embodiment,the system interface unit 70 may include a system NFC recognition unit71 and a system power control unit 72.

The system NFC recognition unit 71 may recognize a case in which theelectronic card 400 moves away from an NFC terminal (or a reader) bysensing a level of DC power flowing into the electronic card 400. Forexample, when the power level begins to decrease below a predefinedreference value, the system NFC recognition unit 71 may sense that theelectronic card 400 moves away from the NFC terminal and supply of powercan be interrupted soon.

However, if it is recognized that the system unit 40 needs tocontinuously operate even after the supply of power is interrupted, thesystem constant voltage unit 30 may be enabled for a predetermined timeperiod through the system power control unit 72.

In an embodiment, the system power control unit 72 may receive a powerlevel sensing signal from the system NFC recognition unit 71. At thispoint, when power of the system unit 40 should be maintained (e.g., whenthe system unit 40 includes a display unit and needs to operate for afew seconds or minutes more), the system power control unit 72 maytransfer a power supply maintaining signal to the voltage levelrecognition unit 60. When the voltage level recognition unit 60 receivesthe power supply maintaining signal from the system power control unit72, the voltage level recognition unit 60 may keep the system constantvoltage unit 30 enabled for a predetermined time period regardless ofthe constant voltage enable signal (a first condition) and the chargedcapacity of the charging unit 20 (a second condition).

This is to make up for the problem of interrupting supply of power tothe system unit 40 as supply of NFC power is interrupted although powershould be supplied to maintain operation of the system unit 40 duringthe operation of the electronic card 400, and this may guarantee stableoperation of the system unit 40.

In another embodiment, the voltage level recognition unit 60 may beimplemented to enable the system constant voltage unit 30 even when theelectronic card 400 is supplied with power through a contact-typereader. In the embodiments described above, although it is described thesystem constant voltage unit 30 receives the constant voltage enablesignal when the voltage level recognition unit 60 is supplied with powerthrough NFC communication, additionally, the system constant voltageunit 30 may be enabled when power is applied by a contact-type interface80.

To describe the power supply method according to the third embodiment,referring to FIG. 5, charge of the charging unit 20 may be performedwhen power is applied (step S510). At this point, application of powerincludes application of power through contactless communication (e.g.,NFC) and application of power supplied to the contact-type interface 80of the COB pad 610 through contact communication. When power is applied,the charging unit 20 may be charged, and although time is required tocharge the charging unit 20 when the charging unit 20 is chargedinitially, the charging time of the charging unit 20 is reducedthereafter by the remaining power.

First, as described above with reference to FIG. 3, the voltage levelrecognition unit 60 may determine enablement or disablement of thesystem constant voltage unit 30 by determining whether the constantvoltage enable signal is applied and determining whether the chargedcapacity is higher than a reference value (steps S520 and S560).

In another embodiment, if power is supplied by the contact-typeinterface 80 even when the constant voltage enable signal is notapplied, the voltage level recognition unit 60 may sense supply of powerand enable the system constant voltage unit 30 (step S530).

In still another embodiment, whether or not to maintain the enabledstate of the system constant voltage unit 30 may be determined throughthe system interface unit 70 (step S540). As described above, the systemNFC recognition unit 71 may recognize a case in which the electroniccard 400 moves away from an NFC terminal (or a reader) by sensing alevel of DC power flowing into the electronic card 400. The system powercontrol unit 72 may receive a power level sensing signal from the systemNFC recognition unit 71.

At this point, there may be a case in which the system power controlunit 72 determines that power of the system unit 40 should bemaintained. For example, it includes a case in which the system unit 40includes a display unit and needs to operate a few seconds or minutesmore, a case in which the sensor of the system unit 40 needs to operatefurther longer or the like. The system power control unit 72 maytransfer a power supply maintaining signal to the voltage levelrecognition unit 60. When the voltage level recognition unit 60 receivesthe power supply maintaining signal from the system power control unit72, the voltage level recognition unit 60 may keep the system constantvoltage unit 30 enabled for a predetermined time period.

When the enablement signal is received from the voltage levelrecognition unit 60, the system constant voltage unit 30 operates tosupply power to the system unit 40 (steps S570 and S580). For example,when the system constant voltage unit 30 is implemented in the form of aswitch, it can be implemented to supply power by turning the switch tothe ON (enabled) state so that power may be supplied to a circuitconnected to the system unit 40.

Although the conditions for enabling the system constant voltage unit 30are described in this embodiment, conditions other than the conditionsS520, S560, S530 and S540 described above may be added to stably supplypower to the system unit 40.

Like this, according to the embodiments of the present disclosure, asthe voltage level recognition unit 60 implements selective enablement ofthe system constant voltage unit 30 through power monitoring, stablecharge of the charging unit 20 is supported, and malfunction of thesystem unit 40 can be prevented. That is, the charging unit 20 may beintensively charged, and consumption of charged power by naturaldischarge may be reduced, and the problem of malfunction of the systemunit generated when power is simultaneously supplied can be solved.

In addition, the present disclosure may be implemented as acomputer-readable code in a computer-readable recording medium. Thecomputer-readable recording medium includes all storage media such as amagnetic storage medium, an optically readable medium, and the like. Inaddition, data formats of the messages used in the present disclosurecan be recorded in the recording medium.

According to the power supply method described in the embodiments of thepresent disclosure, as the method is implemented to supply power to thesystem unit only when NFC power is applied, stable operation of thesystem unit can be supported while reducing the charging time of thecharging unit in the electronic card to the maximum. In addition,natural discharge of the power of the charging unit can be prevented.

In addition, as the voltage level recognition unit of the electroniccard implements selective enablement of the system constant voltage unitthrough power monitoring, the charging unit may be intensively charged,consumption of charged power by natural discharge may be reduced, andthe problem of malfunction of the system unit generated when power issimultaneously supplied can be solved.

The present disclosure has been described in detail focusing on thepreferred embodiments shown in the figures. These embodiments are notintended to restrict the present disclosure and merely for illustrativepurposes only and should be considered from the illustrative viewpoint,not the descriptive viewpoint. The true technical protection range ofthis disclosure should be defined by the technical spirit of theattached claims. Although specific terms have been used in thisspecification, they have been used merely for the purpose of describingthe concept of the present disclosure and have not been used to restrictthe meaning or to limit the scope of the present disclosure disclosed inthe claims. Each step of the present disclosure is not required to beexecuted in the particular order disclosed herein and may be executedparallelly, selectively or individually. It will be understood by thoseskilled in the art that various modified forms and equivalent otherembodiments can be made without departing from the spirit of the presentdisclosure defined in the claims. It should be understood that theequivalents include equivalents that will be developed in the future, aswell as the equivalents publicized in present, i.e., all constitutionalcomponents invented to perform the same functions regardless of astructure.

What is claimed is:
 1. An electronic card comprising: a rectificationunit for generating DC power by converting current induced from anantenna; a charging unit configured to be charged with the DC powersupplied from the rectification unit; a system constant voltage unit forreceiving the DC power together with the charging unit and supplyingpower to a system unit, wherein the system constant voltage unit is in adisabled state until a constant voltage enable signal is generated andis enabled when a predefined condition is satisfied; and the system unitfor receiving power and operating when the system constant voltage unitis enabled.
 2. The electronic card according to claim 1, wherein thepredefined condition includes a first condition that the charging unithas a charged capacity higher than a predefined reference value and asecond condition of receiving the constant voltage enable signal fromthe rectification unit.
 3. The electronic card according to claim 1,further comprising a voltage level recognition unit for monitoring apower supply state to determine whether the predefined condition issatisfied.
 4. The electronic card according to claim 3, wherein thevoltage level recognition unit determines whether the predefinedcondition is satisfied and transmits an enablement signal to the systemconstant voltage unit if the predefined condition is satisfied.
 5. Theelectronic card according to claim 1, wherein the system unit includes amodule for implementing at least one application function provided bythe electronic card and operates using the power received from thesystem constant voltage unit.
 6. The electronic card according to claim3, wherein the predefined condition further includes a third conditionof supplying power through a contact-type interface of the electroniccard, and if power is supplied through the contact-type interface, thevoltage level recognition unit determines that the predefined conditionis satisfied and enables the system constant voltage unit.
 7. Theelectronic card according to claim 3, further comprising a systeminterface unit for grasping an applied power state and a power use stateof the system unit and transferring the states to the voltage levelrecognition unit, wherein the system interface unit includes: a systemNFC recognition unit for sensing a wireless communication signalreceived from the rectification unit; and a system power control unitfor transmitting a power supply maintaining signal to the voltage levelrecognition unit when power of the system unit needs to be maintained.8. The electronic card according to claim 7, wherein the system powercontrol unit receives a potential level reduction signal from the systemNFC recognition unit and transmits the power supply maintaining signalto the voltage level recognition unit if it is determined that power ofthe system unit needs to be maintained.
 9. The electronic card accordingto claim 8, wherein if the power supply maintaining signal is received,the voltage level recognition unit enables the system constant voltageunit for a predetermined time period regardless of whether thepredefined condition is satisfied.
 10. A power supply method implementedin an electronic card, the method comprising steps of: charging acharging unit through DC power supplied from a rectification unit;enabling, when a constant voltage enable signal is applied, a systemconstant voltage unit if a predefined condition is satisfied; andsupplying power to a system unit when the system constant voltage unitis enabled, wherein the system constant voltage unit receives the DCpower together with the charging unit and is in a disabled state untilthe constant voltage enable signal is generated.
 11. The methodaccording to claim 10, wherein the predefined condition includes a firstcondition that the charging unit has a charged capacity higher than apredefined reference value and a second condition of receiving theconstant voltage enable signal from the rectification unit.
 12. Themethod according to claim 10, wherein the enablement step includes stepsof: monitoring a power supply state and determining whether thepredefined condition is satisfied by a voltage level recognition unit;and transmitting an enablement signal to the system constant voltageunit and enabling the system constant voltage unit by the voltage levelrecognition unit when the predefined condition is satisfied.
 13. Themethod according to claim 12, wherein the predefined condition furtherincludes a third condition of supplying power through a contact-typeinterface of the electronic card, and the enablement step furtherincludes the step of: determining that the predefined condition issatisfied and enabling the system constant voltage unit by the voltagelevel recognition unit if power is supplied through the contact-typeinterface.
 14. The method according to claim 12, wherein the enablementstep includes a step of grasping an applied power state and a power usestate of the system unit and transferring the states to the voltagelevel recognition unit by a system interface unit.
 15. The methodaccording to claim 14, wherein the transfer step includes steps of:sensing a potential level reduction signal through the system interfaceunit; and transmitting a power supply maintaining signal to the voltagelevel recognition unit if it is determined that power of the system unitneeds to be maintained.
 16. The method according to claim 15, whereinthe enablement step further includes a step of enabling the systemconstant voltage unit for a predetermined time period regardless ofwhether the predefined condition is satisfied when the voltage levelrecognition unit receives the power supply maintaining signal.